Insertion tool for transmyocardial implant

ABSTRACT

An insertion tool facilitates insertion of a vessel end of a transmyocardial implant into a coronary vessel. The insertion tool has a hollow sheath and mating dilator. The sheath has an external dimension sized for the sheath to be received within a lumen of an expanded size of the coronary vessel. A tapered portion extends from the dilator coaxially with an axis of the sheath. The tapered portion narrows from a cylindrical body portion to a leading tip of the tapered portion. The leading tip of the tapered portion is sized to be received within the lumen of a constricted size of the coronary vessel. The tapered portion and body portion are retractable from the sheath. After such retraction, the leading end of the implant is placed within the sheath. The sheath is split at a part-line such that the sheath can be pulled rearwardly from the vessel without disrupting the coronary vessel following placement of the implant within the sheath.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains to an implant for passing blood flow directlybetween a chamber of the heart and a coronary vessel. More particularly,this invention pertains to an insertion tool to facilitate insertion ofsuch an implant into the coronary vessel.

2. Description of the Prior Art

U.S. Pat. No. 5,755,682 dated May 26, 1998 and PCT Application No.PCT/US97/13980 (International Publication No. WO 98/06356 based U.S.patent application Ser. No. 08/882,397 filed Jun. 25, 1997) teach animplant for defining a blood flow conduit directly from a chamber of theheart to a lumen of a coronary vessel. An embodiment disclosed in theaforementioned patent and applications teaches an L-shaped implant inthe form of a rigid conduit. The conduit has one leg sized to bereceived within a lumen of a coronary artery and a second leg sized topass through the myocardium and extend into the left ventricle of theheart. As disclosed in the above-referenced patent and applications, theconduit is rigid and remains open for blood flow to pass through theconduit during both systole and diastole. The conduit penetrates intothe left ventricle in order to prevent tissue growth and occlusions overan opening of the conduit.

Commonly assigned and co-pending U.S. patent application Ser. No.08/944,313 filed Oct. 6, 1997, entitled “Transmyocardial Implant”teaches an implant such as that shown in the aforementioned '682 patentwith an enhanced fixation structure. The enhanced fixation structureincludes a fabric surrounding at least a portion of the conduit tofacilitate tissue growth on the exterior of the implant.

Implants such as those shown in the aforementioned applications includea portion to be placed within a coronary vessel and a portion to beplaced within the myocardium. When placing a portion of the implant inthe coronary vessel, the vessel is axially incised a length sufficientto insert the implant. Such an incision results in a contraction of thecoronary vessel to a size substantially smaller than the implant.Therefore, it is difficult to insert the implant into the lumen of thecoronary vessel. Such vessels are elastic and can be urged to anexpanded shape sufficient to fit over the implant. However, due to thesmall size of the vessel, restricted space for manipulating surgicaltools, and the importance of avoiding damage to the coronary vessel,such a manipulation of the vessel is difficult.

SUMMARY OF THE INVENTION

According to a preferred embodiment of the present invention, aninsertion tool is disclosed for facilitating insertion of a vessel endof a transmyocardial implant into a coronary vessel. The transmyocardialimplant has a hollow conduit for establishing a blood flow path througha myocardium between a heart chamber and a lumen of a coronaryvasculature residing on an exterior of said wall. The vessel end has anexternal geometry for the vessel end to be received within the lumen.The vessel end has a generally tubular external geometry and an axialopening at a leading end. The coronary vessel has a constricted size andis expandable to a larger expanded size. The insertion tool includes asheath having an external dimension sized for the sheath to be receivedwithin the lumen of the expanded size of the coronary vessel. A dilatoris removably inserted through the sheath. A leading end of the dilatoris sized to be received within the lumen of the constricted size of thecoronary vessel. The dilator is removed from the sheath after placementof the dilator and sheath in the vessel. The implant is then placed inthe sheath. The sheath is retracted from the vessel without disruptingthe coronary vessel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of an implant for use with the presentinvention;

FIG. 2 is the view of FIG. 1 showing the implant of FIG. 1 and showing,in cross section, a tissue growth-inducing material secured to anexterior of the conduit and showing the implant positioned within themyocardium and lumen of a coronary vessel;

FIG. 3 is a side-elevation view of an insertion tool according to thepresent invention;

FIG. 4 is the view of FIG. 3 and showing dilator and sheath componentsseparated;

FIG. 5 is an enlarged view of the dilator inserted within the sheath andshowing the sheath in cross-section; and

FIG. 6 is a rear, bottom and side perspective view of the sheath.

DESCRIPTION OF THE PREFERRED EMBODIMENT

With initial reference to FIG. 1, a conduit 10 is shown in the form ofan L-shaped rigid tube. The conduit 10 may be formed of titanium orother rigid biocompatible material such as pyrolytic carbon or may betitanium coated with pyrolytic carbon. The material of the conduit 10 ispreferably a rigid material in order to withstand contraction forces ofthe myocardium. By way of example, the tube will have an outsidediameter D_(o) of about 3.0-2.0 millimeters and an internal diameterD_(I) of about 2.5-1.5 millimeters to provide a wall thickness of about0.5 millimeters.

The tube 10 has a first portion (or vessel end) 12 sized to be receivedwithin the lumen of a coronary vessel such as the lumen 100 of acoronary artery 102 illustrated in FIG. 2. The conduit 10 has a secondportion (or myocardium end) 14 extending at a right angle to the axis ofportion 12. The second portion 14 is sized to extend from the coronaryartery 102 directly through the myocardium 104 and protrude into theleft ventricle 106 of a patient's heart. The second portion 14 is sizedto have a length sufficient for the portion 14 to protrude into the leftventricle 106.

The vessel end 12 has a first opening 16 and the myocardium end 14 has asecond opening 18 in communication with an interior 20 of the implant10. Therefore, blood can freely flow through the implant 10 between theleft ventricle 106 and the lumen 100 of the coronary artery 102. Aleading end 22 of the vessel end 12 is tubular.

As illustrated in FIGS. 1 and 2, grooves 24, 26 are formed spaced-aparton the myocardium end 14. A sleeve 52 includes a first end 54 withsutures 56 disposed around end 54 to retain end 54 within the groove 24.The material at the first end 54 is folded over the sutures 56 andstitched by stitching 58 to secure the first end 54 in the groove 24 andto immobilize the first end 54 relative to the tube 10. Similarly, asecond end 60 of the sleeve 52 is retained by sutures 62 in the groove26 and threading 64 secures the material of the sleeve 52 over thesutures 62. In the figures, the stitching 58,64 is shown exposed on anexterior of the sleeve 52. Alternatively, the sleeve 52 can be formedinverted so that the stitching 58,64 is not exposed.

Preferably, the sleeve 52 is formed of a fabric having biocompatiblefibers defining interstitial spaces to receive tissue growth. An exampleof such a fabric is polyethylene terephthalate (such as polyester fabricsold by DuPont Company under the trademark Dacron). Such a fabricpermits rapid tissue integration into the fabric to anchor the fabricand, hence, the tube 10 to the patient's tissue. Additionally, the firstportion 12 is secured in place by means of a reduced-diameter groove 13formed adjacent the leading end 22. With the reduced-diameter groove 13,a surgeon can place sutures 70 surrounding the coronary artery 102 tosecure the coronary artery 102 immobilized at the groove 13.

The foregoing description with reference to FIGS. 1 and 2 is providedfor illustration and is more thoroughly described in the aforementionedU.S. patent application Ser. No. 08/944,313 entitled “TransmyocardialImplant”.

In one method of placing the vessel end 12 into the artery 102, anincision 83 is made on an upper surface of the artery 102 distal to acoronary obstruction 85. The portion of the artery 82 proximal to theimplant 10 is closed by sutures 88.

The process of incising the artery 102 results in contraction of theartery 102 to a reduced diameter. For example, an artery 102 such as theleft anterior descending artery (LAD) may contract down to 0.5 mm. Thisis smaller than the diameter of the leading end 22 of the implant 10.The artery 102 is elastic and may be expanded to an enlarged expandeddiameter (eg., 2-5 mm). However, it is difficult to manipulate tools toexpand the artery 102 due to the small space available to work.

To facilitate placement of the implant 10 within the vessel 102, a novelinsertion tool 200 is disclosed. The insertion tool 200 includes asheath 201 and a mating dilator 203.

The sheath 201 includes a straight handle 205. A sheath funnel 207 issecured to an end of the handle with a funnel axis X—X perpendicular tothe handle 205. A bottom side 209 of the funnel 207 is cut-away. Thefunnel 207 tapers from a large diameter trailing end 211 to a narrowleading end 213. The inner diameter of the trailing end 211 is largerthan the outside diameter of the implant's leading end 22. The insidediameter of the leading end 213 is the same or only slightly larger thanthe outside diameter of the implant's leading end 22. By way ofnon-limiting example, for an implant 10 having an outside diameter D_(o)of 2.5 mm, the inside diameter of the funnel training end 211 is 5.5 mmand the inside diameter of the of the funnel leading end 213 is 2.5 mm.

A hollow, cylindrical sheath body 215 is secured to the leading end 213of the funnel 207. The cylindrical axis of the sheath body 215 isco-linear with axis X—X. In the foregoing example, the sheath body willhave a substantially uniform inside diameter of 2.5 mm and, except aswill be described, an outside diameter of 2.7 mm. At its leading end217, the outside diameter of the sheath body 215 is tapered down to 2.5mm. Preferably, the leading end 215 is rounded so as not to present asharp edge to a coronary vessel upon insertion.

On a side of the sheath body 215 opposite handle 205, the sheath body215 is scored by a score line 219 running axially the entire length ofthe sheath body 215. The score line 219 may be a partial cut through thematerial of the sheath body 215 to weaken the material such that uponapplication of force, as will be described, the sheath body 215 willtear along the score line 219. Alternatively, the score line 219 can bea lengthwise through-cut (as shown in the drawings) or can be a seriesof holes to define a perforation line.

The dilator 203 has cylindrical body portion 202 and a conical, taperedportion 204. The tapered portion 204 extends axially from the bodyportion 202. The opposite end of the body portion 202 is provided with ahandle 206 to permit grasping of the dilator 206. The handle 206projects at a 90° angle to the axis of the body portion 202.

The dilator body portion 202 is sized with an outside diameter the sameor slightly larger than the inside diameter of the sheath body 215. Inthe example given, the body portion has an outside diameter of 2.5 mm.The tapered portion tapers to a rounded leading end 208 which, in theexample given, has a diameter of 1.0 mm.

The dilator 203 is secured to the sheath 201 by the dilator handle 206being releasably secured in clips 319 on the sheath handle 205. With thedilator 203 so secured to the sheath 201, the dilator body portion 202is slidably received within the sheath body 215 and the dilator taperedportion 204 protrudes beyond the sheath leading end 217.

The leading end 208 of the tapered portion 204 is sized to have adiameter sufficiently small for the leading end 208 to slip into thelumen 100 of the contracted size artery 102. Further advancement of thedilator and sheath dilates the vessel. A small portion of the fulldiameter dilator body 202 extends beyond the sheath leading end 217 sothe vessel is fully dilated before the sheath body 215 is urged into thevessel.

The contracted size artery 102 can easily slip over the leading end 208of the dilator 203. Both the dilator and sheath may be lubricious toease insertion into the vessel. As a result of such insertion, theartery 102 expands to an expanded size surrounding the sheath body 215.

With the sheath 201 and dilator 203 fully inserted into the artery 102,the dilator 203 can be removed. The implant leading end 22 is thenplaced in the sheath body 215. Specifically, the implant leading end 22is inserted into the guide funnel 207. The guide funnel 207 directs theimplant leading end 22 into the cylindrical sheath body 215. Soinserted, the leading end 22 of the implant 10 is inserted into theartery 102 and the sheath body 215 is positioned between the implant 10and the artery 102 protecting the artery 102 from trauma.

After placement of the implant 10, the sheath 201 can be removed. Thephysician simply pulls on handle 205. This imparts a force which splitsthe score line 219. With the score line 219 split, the surgeon can pullthe sheath body 215 rearwardly out of the vessel 102. The flexiblematerial of the sheath body 215 spreads apart at the bend of the implant10 to pass the split sheath body 215 over the bend so that the sheathbody 215 can be removed without disrupting the position of the artery102 over the implant's leading end 22. Instead, any frictional forcebetween the artery 102 and the sheath body 215 will tend to further urgethe artery 102 over the leading end 22. Therefore, the artery 102remains over the leading end 22 of the implant 10 and surrounding groove13 so the artery 102 can be fixed to the implant 10 with sutures 70(FIG. 2) surrounding groove 13.

Having disclosed the present invention in a preferred embodiment, itwill be appreciated that modifications and equivalents may occur to oneof ordinary skill in the art having the benefits of the teachings of thepresent invention. It is intended that such modifications shall beincluded within the scope of the claims appended hereto.

What is claimed is:
 1. A tool for facilitating insertion of a vessel endof a transmyocardial implant into a coronary vessel, saidtransmyocardial implant having a hollow conduit for establishing a bloodflow path through a heart wall between a heart chamber and a lumen of acoronary vessel residing on said heart wall, said vessel end having anexternal geometry for said vessel end to be received within said lumen,and said vessel end having a generally tubular external geometry and anaxial opening at a leading end, said coronary vessel having constrictedsize and expandable to a larger expanded size, said insertion tipcomprising: a sheath having an internal volume sized to receive saidleading end of said implant, and sheath having an external dimensionsized for said sheath to be received within said lumen of said expandedsize of said coronary vessel, wherein said sheath includes a score atleast partially through a thickness of said sheath and extending anpartial axial length of said sheath; a dilator sized to be receivedwithin said internal volume and having a dilator leading end sized to bereceived within said lumen of said constricted size of said coronaryvessel; and wherein said dilator includes a generally cylindrical bodyportion sized to be snugly received within the internal volume of saidsheath and said dilator leading end is a taper from the cylindricalportion to a leading tip of said dilator.
 2. A tool for facilitatinginsertion of a vessel end of a transmyocardial implant into a coronaryvessel, said transmyocardial implant having a hollow conduit forestablishing a blood flow path through a heart wall between a heartchamber and a lumen of a coronary vessel residing on said heart wall,said vessel end having an external geometry for said vessel end to bereceived within said lumen, and said vessel end having a generallytubular external geometry and an axial opening at a leading end, saidcoronary vessel having constricted size and expandable to a largerexpanded size, said insertion tip comprising: a sheath having aninternal volume sized to receive said leading end of said implant, andsheath having an external dimension sized for said sheath to be receivedwithin said lumen of said expanded size of said coronary vessel; adilator sized to be received within said internal volume and having adilator leading end sized to be received within said lumen of saidconstricted size of said coronary vessel; and wherein said sheathincludes a score at least partially through a thickness of said sheathand extending an axial length of said sheath.
 3. A tool according toclaim 1 where said score is formed completely through a wall-thicknessof said sheath.
 4. A tool for facilitating insertion of a vessel end ofa transmyocardial implant into a coronary vessel, said transmyocardialimplant having a hollow conduit for establishing a blood flow paththrough a heart wall between a heart chamber and a lumen of a coronaryvessel residing on said heart wall, said vessel end having an externalgeometry for said vessel end to be received within said lumen, and saidvessel end having a generally tubular external geometry and an axialopening at a leading end, said coronary vessel having constricted sizeand expandable to a larger expanded size, said insertion tip comprising:a sheath having an internal volume sized to receive said leading end ofsaid implant, and sheath having an external dimension sized for saidsheath to be received within said lumen of said expanded size of saidcoronary vessel; a dilator sized to be received within said internalvolume and having a dilator leading end sized to be received within saidlumen of said constricted size of said coronary vessel; and wherein saidsheath includes a guide funnel on a trailing end of said sheath.